Overclocking of 1090T was done using a solid voltage bump up to 1.50 V, and increasing the unlocked multiplier until the maximum stable frequency is reached. In this case, using a small Scythe Katana III cooler, the best stable result was 4100 MHz, which is an excellent result for an AMD processor. Especially considering we're dealing with six beefy cores here.
Six overclocked cores certainly sounds good, it might be just as bad. Power consumption jumps through the roof, and you will be needing a massive CPU cooler to keep temperatures in check. If you want to keep it at maximum stable clocks, that is. For some medium overclocking, say 3600-3800 MHz on all cores might be achieved with just a small voltage increase over stock settings, which means no drastic changes in temperatures or power consumption. All in all, great results as far as overclocking goes, and performance of the overclocked processor for that matter.